As portable electronic devices become more compact, and the number of functions performed by a given device increases, it has become a significant challenge to design a user interface that allows users to easily interact with a multifunction device. This challenge is particularly significant for handheld portable devices, which have much smaller screens than desktop or laptop computers. This situation is unfortunate because the user interface is the gateway through which users receive not only content but also responses to user actions or behaviors, including user attempts to access a device's features, tools, and functions. Some portable communication devices (e.g., mobile telephones, sometimes called mobile phones, cell phones, cellular telephones, and the like) have resorted to adding more pushbuttons, increasing the density of push buttons, overloading the functions of pushbuttons, or using complex menu systems to allow a user to access, store and manipulate data. These conventional user interfaces often result in complicated key sequences and menu hierarchies that must be memorized by the user.
Many conventional user interfaces, such as those that include physical pushbuttons, are also inflexible. This is unfortunate because it may prevent a user interface from being configured and/or adapted by either an application running on the portable device or by users. When coupled with the time consuming requirement to memorize multiple key sequences and menu hierarchies, and the difficulty in activating a desired pushbutton, such inflexibility is frustrating to most users.
As a result of the small size of display screens on portable electronic devices and the potentially large size of electronic files, frequently only a portion of a list or of an electronic document of interest to a user can be displayed on the screen at a given time. Users thus will frequently need to scroll displayed lists or to translate displayed electronic documents. Users also will need to rotate and to scale (i.e., magnify or de-magnify) displayed electronic documents. However, the limitations of conventional user interfaces can cause these actions to be awkward to perform.
Furthermore, scrolling displayed lists and translating electronic documents can be awkward on both portable and non-portable electronic devices with touch-screen displays. A user may become frustrated if the scrolling or translation does not reflect the user's intent. Similarly, a user may become frustrated if rotation and scaling of electronic documents does not reflect the user's intent.
Accordingly, there is a need for devices with touch-screen displays with more transparent and intuitive user interfaces for scrolling lists of items and for translating, rotating, and scaling electronic documents that are easy to use, configure, and/or adapt.